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The math of diabetes: Comparison is the death of happiness… with your insulin doses

article by Alicia

One of the wisest quotes is “Comparison is the death of happiness”. No one really knows to whom this quote should be credited, or even the precise wording, but the sentiment and wisdom is undeniable. It applies to every area of life, yes, even our diabetes management.

We can exhaust our brains looking for information on what is “normal” in diabetes.

  • How much insulin does the average adult use?
  • What is a normal insulin-to-carb ratio for a 6-year-old?
  • How much insulin does someone’s body produce who does not have diabetes?

These numbers are difficult if not impossible to find, and when they are found they often represent ranges too wide to be meaningful.

For example, one article sites that “The amount of insulin produced by a lean, healthy individual is usually between 18 and 40 U/day or 0.2–0.5 U/kg/day.”

*You don’t need to know anything about insulin to know that a variability of more than 100% is massive. And that variability is in the SAME type of person. Same gender, same BMI, same health status. When we begin to factor in differences between two people who are not cherry-picked from this “lean healthy” (See also WHITE, MALE, between18-35 because that is the demographic that the vast majority of the last 100 years of our American medical information has come from)  pool of individuals we can expect insulin needs to vary wildly, with some people needing very little insulin over the course of a day, and others needing many times that amount to meet the needs of a very different self.

learning insulin

Where do we begin? When someone is “insulin naïve” having never used insulin before we must start entirely with math to guess where to start their dosing.

We often only have one piece of information to use to start this decision-making, the person’s weight. The calculation for total insulin usage is based on the above-stated assumption that if we had a “human template” (not an actual person, but more of a conceptual prototype) they would most likely use 0.5 units in insulin per kg of body weight. This Human Template would also use ½ of that insulin for basal insulin needs, and the other half to cover mealtime insulin needs. This is the very beginning of how we begin insulin delivery dosage.

From here we have a few options.

  • Best case scenario we can talk to our REAL LIFE human and inquire about their daily caloric intake, dietary practices, physical activity and even measure their BMI and body composition to determine their most likely starting insulin sensitivity (also known as correction factor) and carbohydrate ratios.


  • We can go back to our human template and make a bunch of assumptions based on the “Average American” Caloric intake. We can use the person’s total daily dose of insulin (determined by our template human math above) and divide that into the assumed caloric intake from our Template human(1500, 1700, 1800 there is even some discussion over which is appropriate to use in different populations)  to get a Sensitivity. Likewise, for carb ratio we just divide that Template derived total daily dose into the “Average American Carb Use” daily (500 a number derived from carbs eaten as well as those derived from non carb sources).

As you can see the math is a very ASSUMED number based on a lot of ASSUMED information about an ASSUMED person that can not possibly actually exist in the real world! Therefore, the initial insulin dosing we get at diagnosis is usually a complete disaster. It leads us to immediately question everything our clinicians are doing and telling us and seeking answers the only way we have readily available; by comparing ourselves to those around us.

The proof of the pudding’s in the eating
– Early 17th century colloquialism

How we get from the mess of the assumed math of diabetes to the refined individualized math that really works well is through a few processes.

We start with basal testing, because it’s the foundational base on which the rest is built. This is essentially an observation of how basal is working and we raise or lower basal dosage to achieve as close to a flat line as we can when not eating or exercising. This can vary wildly from person to person and even within a single day for a given individual. It also changes as we grow, age and move through different hormonal phases of life.

Carb ratios can be tested by eating a well-measured meal, calculating the insulin dose to match the meal precisely, then observing the action. The correct dose should return blood sugar to its starting point in roughly 3-4 hours of dosing. The amount of insulin needed to return the meal to starting blood sugar, divided into the total carb count of the meal = the carb ratio. This ratio can vary throughout the day in any given individual as well. For this reason, a clinician will typically adjust carb ratios based on how well they work overtime, rather than having patients do repeated testing.

Sensitivity or correction factors can, likewise be “tested” by purposely having elevated blood sugar (but not above 250mg/dl) and taking a set dose of correction insulin. Measuring how far BG drops over a 3–4-hour period before leveling out and dividing that drop in BG by the amount of insulin given. Like carb ratios this sensitivity can change throughout the day, and so again, most clinicians will base adjustments on overall efficacy rather than putting patients through repeated testing.

Remember that all carb and sensitivity settings are based on the assumption that basal levels are appropriate first. No amount of adjustment of ratios can make up for basal settings that are off, because the moment basal needs change the whole foundation gets shifted and the ratios built on that no longer work.

Never has comparison been easier, more available, or more toxic than in our modern diabetes world.

Sharing information and support is fantastic, but the moment we start comparing we are expecting to find validation or direction by being like others. But what we truly find is frustration and further dissatisfaction. If we are seeking answers to math problems, we should seek answers from our peers, but even then, we must be able to identify those who KNOW the concepts involved. Taking the solutions from someone who got the wrong answer will not help. But taking the answer from someone who got the right answer but by the wrong logic may also be even worse. Because that wrong logic will lead us farther and farther from being able to solve any other math problem. Diabetes management is FAR from the straightforward simplicity of math (Spoken by someone who really hates math! And finds nothing at all simple in it!) The nuanced individuality of diabetes means that copying someone else’s answer will simply not work. At BEST we can seek someone who’s LOGIC is correct.

When we teach people with diabetes, we must begin with the basic math.

This is the rudimentary information to stay alive while using insulin. However, to thrive while using insulin we move from basic math into teaching logic. The principals of physiology, insulin action (Pharmacology) nutrition and their technology so that they can apply that logic to their diabetes management in dynamic and meaningful ways so that the math can then function for them as individuals. I call this the “art” of diabetes. And it makes up easily 30% of good stable diabetes management. And is critical to maintaining a life with diabetes that makes sense and has a sense of stability, empowerment, and peace because math only makes up about 60% of diabetes management. Without the “Art”, the math often does not do what is expected!

Your carb ratios might be perfect, but digestive timing, protein content, fat content, physical activity, hormones, and digestive issues may be playing a part in certain meals. Likewise, sensitivity may be impacted by activity levels, stress levels, hormones, weight shifts, body composition, climate, altitude, even the size of the insulin dose taken can change how it works!

We could easily have two of our “human templates” using the exact same amounts of insulin, with the same ratios, eating the same diets, who could easily have wildly different results in their blood sugar outcomes. All because of what they are doing with the “art” of their diabetes management, and the fundamental differences of who they are as people.

Framework is not Comparison

If comparison is so bad, why do we use so many clinical markers and goals in medicine? This is because having a framework in which to work is helpful. Knowing at what point a therapeutic need indicates that there may be a secondary issue to address is a very useful tool. For example, comparing how much I spend on my vacation to how much my friend spends on their vacation is not healthy. The two are unrelated and have no meaningful bearing on one another. However, knowing the average annual pay range of someone in my career field is a helpful framework in which to assess whether I am being paid fairly for my work. There is an established set of norms, and even more meaningfully, being outside of those norms is indicative of certain positive or negative attributes that I should be aware of for improvement or building upon.

In diabetes management we should keep our insulin needs within a framework of established norms and be aware of where there are indicators of increased risks of benefits. We should not compare to others. As we have illustrated above, there is no meaningful bearing of insulin needs from one person to another. As clinicians we look to some of the following framework indicators with regards to insulin needs as indicators of potential secondary concerns or benefits

Insulin needs greater than 1 unit/ kg of body weight: This may indicate insulin resistance. Insulin resistance is common for many adults with diabetes but may also be associated with increased cardiovascular risks and other metabolic or endocrine issues. It would also be an irregular finding in a child. When might this be a more typical finding? In a teen or growing child with a higher than typical carb intake insulin use may be quite high. Likewise, someone who is focusing on trying to gain weight, muscle, recovering from severe injury or illness, and of course the physical rigors of pregnancy could all lead to higher than typical insulin needs.

Insulin needs lower than 0.3 units/kg: This may be of concern for many reasons including diabetes-anorexia, weight loss, DKA risk, GI issues like malabsorption, Hyperthyroidism, Addison’s disease, or other endocrine disease. This may however be completely normal for someone on a low carb diet who is very physically active.

Typical insulin need models: Different stages of life typically have predictable patterns of insulin need. For example, most young children see a spike of insulin need at bedtime, most adults will see a rise in insulin needs in the early morning and a reduced need in the mid-afternoon. Seeing a shift in one’s established pattern may indicate a change in one’s stage of life such as entering or exiting puberty, menopause, growth spurts, etc. The absence of typical patterns may also indicate other endocrine issues if they are accompanied by symptoms of that issue and can help clue clinicians into a struggle a patient may be experiencing. I have seen plenty of adults who have an evening basal need much higher than their early morning need, and children who see a significant basal need in the morning. So, the presence or lack of a pattern feature does not, in isolation, indicate anything at all.

Sudden changes in insulin needs: If a clinician sees a marked change in the insulin needs of an individual, they should immediately look into what may have caused this change. Insulin needs should change over time as we grow, change activities, life stages and roles. But sudden changes should be investigated as potential indicators that something physiologically has changed and may need further attention. Children may see marked insulin needs in time of growth or illness. But these amounts are typical for children (30-50% during a growth spurt is very common) but to see the change in insulin need with no other evidence of growth (fatigue, mood changes, increased appetite, complaints of aches, clothing becoming ill-fitting) would be cause for further investigation. In someone with female reproductive processes seeing insulin needs increase 50% up or down during certain cycle days is very typical and not cause for concern. But seeing this continue for more than 5-7 days in a row would not be typical for menstrual hormone cycles and may indicate a secondary issue or a hormonal imbalance that may need further diagnostic attention.  Generally, any insulin need change of more than 30% that can not be explained should be raised with your healthcare provider to discuss possible causes and further investigation if a cause is not apparent.

For more information on diabetes math, you can check out our article “If Diabetes Management Was Math It Would Be Easy“.

And for more information on Insulin resistance indicators check out our article “How Can I Tell If I’m Insulin Resistant

To sharpen your skills on “The Art of Diabetes Management”, and get solid education to build a strong framework and escape the trap of comparison, reach out to schedule an appointment with our knowledgeable and compassionate diabetes experts who go way past the “human template” to outfit you with the tools and skills to master the “art” of diabetes management while helping guide you in making the most of the math.

*Ramchandani N, Ellis MK, Jain S, Bhandari S, Anhalt H, Maclaren NK, Ten S. Basal insulin requirements on continuous subcutaneous insulin infusion during the first 12 months after diagnosis of type 1 diabetes mellitus. J Diabetes Sci Technol. 2010 May 1;4(3):610-4. doi: 10.1177/193229681000400315. PMID: 20513327; PMCID: PMC2901038.

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